Fall 2014 Frost/Freeze Info...Including Average and Observed Dates of First Fall Freeze (Updated Oct. 15)

As of Oct. 15, a pretty good-sized chunk of the the NWS Hastings coverage area in South Central Nebraska and North Central Kansas has now experienced at least one 32°-or-slightly-colder freeze this fall (along with frost), although conversely most places have not yet observed a "true hard freeze" of 28°-or-colder. A few places actually notched one of their earliest freezes on record way back on Sep. 13th (more on that below).  Many of these same areas (along with some additional areas) again dropped slightly below freezing on the mornings of Oct. 4 and Oct 11. Please see the "Looking Back..." section just below for more details on what has transpired thus far this fall...

**  As of Oct. 14:  NWS HASTINGS WILL NO LONGER ISSUE FROST ADVISORIES/FREEZE WARNINGS this fall for its 30-county coverage area (including North Central Kansas). Although not every single place has verified a freeze of 32°-or-colder this fall, the majority of the area (even in KS) has met this threshold at least once, and furthermore, most places have experienced at least one round of frost. As a result, NWS Hastings will cease issuing frost advisories/freeze warnings until May 2015 for the spring growing season (if warranted). **


Looking AHEAD: ** Fall 2014 Potential-for-Freeze Forecast (as of Oct. 15) **:  For the Oct. 16-22 time frame,  there is currently only one night that looks like an "increasingly-likely candidate" for frost formation within parts of the NWS Hastings coverage area, and that is Friday night into the morning of SAT. OCT. 18, when low temperatures are forecast to bottom out in the low-mid 30s range across primarily South Central Nebraska. Beyond the 18th, overnight lows are forecast to "safely" average between the upper 30s-mid 40s across most of the local area through at least the 22nd. In other words, there is no widespread hard freeze of 28°-or-colder currently in sight for South Central Nebraska and North Central Kansas. Please note this is preliminary forecast information and is always subject to change as new data arrives.
 

Looking BACK: What's Already Happened This Fall With Frost/Freeze? (Current as of Oct. 15) **: 
Here is a brief summary of the progression of frost-supportive and freezing temperatures across the area this fall, in "reverse chronological" order:

  • Oct. 11: Although most of the 30-county area still managed to avoid a true hard freeze of 28°-or-colder, the majority of locations did in fact drop into the 29-34° range, bringing a fairly widespread round of morning frost. Per the NWS cooperative observer network, along with a few automated airport sites, a few stations that notched their first 32°-or-colder freeze of the season included: Hastings airport (32°), Aurora airport (31°), 3N York (29°), Hebron (31°). Although not widespread in nature, a few places did notch their first 28°-or-colder hard freeze of the season, including: Greeley (28°), Cambridge (28°), Franklin (28°).
  • Oct. 4: Although a thin veil of high clouds and a light westerly breeze kept temperatures across parts of the area just a touch warmer than expected, morning lows across most of the NWS Hastings coverage area bottomed out in the 29-34° range, or readings fairly similar to those observed back on Sep. 13. The highest concentration of readings of 32° or slightly lower occurred in northern and western locations such as Ord, Greeley, Lexington and Edison, although at least isolated locations farther south and east briefly touched the freezing mark for the first time this fall as well, including official NWS stations at Kearney airport, Holdrege and the Hastings NWS Office (Hastings airport remained just above freezing with a low of 33°). As a result, parts of the area observed another round of frost, but the vast majority of the 30-county NWS Hastings coverage area has yet to observe a true hard, killing freeze of 28° or colder.
  • Sep. 13: An unusually chilly airmass for the first half of September invaded the Central Plains mainly between the 11th-13th. During the day on both the 11th and 12th, most of the local area only recorded high temperatures between the upper 40s-mid 50s. Then, just before this colder air departed the area, it set the stage for a particularly chilly morning on the 13th as the majority of South Central Nebraska and North Central Kansas bottomed out between 33-36°, resulting in the first "frost event" of the fall in many areas. Depending on which portion of the local area one resides in, this first fall frost of 2014 arrived anywhere from 10 to 25 days earlier than average! Although limited in nature, at least small portions of the local area even recorded their first freezing temperatures of the fall, generally dropping to between 29-32°, including NWS cooperative observer stations at Cambridge NE, Alton KS and Beloit KS. At all three of these locations, this was the earliest fall freeze of at least the past 30 years (see table below), and was also one of the earliest first freezes on record. Here are a few site-specific notes about the chilly readings on the morning of 9-13-2014: 

      - Cambridge: With a low of 32°, this tied with 9-13-1949 for the 2nd-earliest freeze on record behind only 9-3-1974
      - Beloit KS: With a low of 32°, this was the 2nd-earliest freeze on record, trailing only 9-10-1894
      - Alton KS: With a low of 29°, this tied with 9-13-1974 for THE EARLIEST freeze on record 
      - Hastings airport: With a low of 35°, this tied with 9-13-1949 for the earliest 36°-or-colder (frost-supportive) reading on record


    Before continuing, here are a few definitions: 
     

    - Frost occurs when there is a solid deposition of water vapor from the air. Frost will form when solid surfaces are cooled below the dew point. An air temperature range of 33-36° along with very light winds are usually needed to initiate frost formation. Minor damage is possible to some plants. One must keep in mind that a frost is not guaranteed at these temperatures if moisture in the air is lacking. The range of average dates for the first occurrence of fall frost across most of south central Nebraska and north central Kansas is between Sep. 23 - Oct. 8.

    - Freeze occurs when the air temperature drops to 32° or lower. A freeze will result in significant damage to many unprotected plants, especially if the temperature remains at the freezing mark for a few hours. The range of average dates for the first freeze of the fall across most of south central Nebraska and north central Kansas is between
    Sep. 28 - Oct. 15.


    - Hard Freeze occurs when the temperature reaches 28° or lower for at least a few hours. It usually means that many types of plants and most seasonal vegetation will be destroyed. The range of average dates for the first hard freeze of the fall across most of south central Nebraska and north central Kansas is between Oct. 6 - Oct. 25.


    The Midwestern Regional Climate Center produces maps that update DAILY, depicting sites across the region that have fallen to at least 32° or 28° so far this fall.  Check out statewide maps of Kansas and Nebraska by clicking on the images below. Again, these maps automatically update daily, and originate from the  Midwest Climate Watch website.

    (Click images to enlarge)

    Kansas observed 32 degrees or below so far this fall

    Nebraska observed 32 degrees or below so far this fall

    Kansas observed 28 degrees or below so far this fall

    Nebraska observed 28 degrees or below so far this fall

     



    Below is a table and set of maps, primarily focused on average dates for reaching particular temperature frost/freeze thresholds. However, there is often tremendous variation from year-to-year and between any given location across the area (see bottom of page for details on unusually early freeze in September 1974).

    Examining the table below, here are a few things to consider:

    - The first column lists 9 chosen locations in south central Nebraska and 4 in north central Kansas with long histories of being NWS Cooperative Observer sites (except for Grand Island and Hastings airports, which are automated systems). This is just a small sampling of dozens of observing locations within the NWS Hastings coverage area, and these sites are generally organized from north to south down the column.

    - The second column shows the average date of the earliest observance of 36, 32, and 28 degree temperatures during the most recent 30-year period from 1984-2013. Please note that differences in average freeze dates between these locations are NOT purely a function of "north versus south", but also depend on a variety of factors including local terrain. For example, Alton, KS, in Osborne County is typically prone to earlier freezes in the fall than some locations farther north, thanks to efficient cold air drainage along the South Fork Solomon River valley.

    - The third and fourth columns reveal the earliest first freeze date and latest first freeze date (32 degrees or colder) observed during the past 30 years, covering the period 1984-2013. It is readily apparent that the phrase "average freeze date" is quite relative, as most sites have a 5-7 week difference between the earliest and latest dates. For the majority of locations, the earliest last freeze during the past 31 years occurred between Sep. 15th-22nd in years such as 1991 and 1993. On the opposite spectrum, for many locations the latest freeze during the past 31 years occurred between Oct. 23th- Nov. 4th in years such as 1997 and 1998.

    - The final column on the right is a work in progress, revealing the date that 36, 32 and 28-degree thresholds are first met THIS FALL within the area. A blue-shaded date indicates a location that reached a temperature threshold at least 10 days before the average date, while red-shaded dates indicates that this threshold was met at least 10 days after the average date.

     Climatological Data For South Central Nebraska and North Central Kansas
    (all averages based on 30-year observations from 1984-2013)

     

    Average First 
    Fall Date of...

    36 Degrees
    32 Degrees
    28 Degrees

    Earliest Date 
    1984-2014 of...

    First Fall 32°
    or Colder 

    Latest Date 
    1984-2014 of...

    First Fall 32°
    or Colder 

    First Fall 2014  
    Occurence of...

    36° or colder
    32° or colder
    28° or colder

     Greeley

    Sep. 23
    Sep. 28
    Oct. 6

    Sep. 15,1993 

    Oct. 13, 2013
    Oct. 13,1997

    Sep 13 (34°)
    Oct 4 (31°)
    Oct 11 (28°)

     Osceola

    Oct. 1
    Oct. 9
    Oct. 14

    Sep. 19, 1991

    Nov. 3, 1998

    Sep 13 (36°)
    ?
    ?

     Kearney Airport
    (NWS Observer)

    Sep. 27
    Oct. 6
    Oct. 15

    Sep. 19, 1991

    Oct. 25, 1997 

    Sep 13 (36°)
    Oct 4 (32°)
    ?

     Grand Island
     (airport)

    Sep. 29
    Oct. 8
    Oct. 15

     Sep. 19, 1991

     Oct. 26, 2007

    Sep 13 (36°)
    ?
    ?

     York

    Oct. 1
    Oct. 9
    Oct. 18

     Sep. 19, 1991

    Nov. 4, 1998

    Sep 13 (34°)
    Oct 11 (29°)
    ?

     Cambridge

    Sep. 25
    Oct. 3
    Oct. 13

    Sep. 13, 2014

     Oct. 25, 1997

    Sep 13 (32°)
    Sep 13 (32°)
    Oct 11 (28°)

     Holdrege

    Oct. 2
    Oct. 9
    Oct. 19

    Sep. 20, 1991

    Nov. 4, 1998

    Sep 13 (35°)
    Oct 4 (31°)
    ?

     Hastings
    (NWS Office/airport)

    Sep. 30
    Oct. 9
    Oct. 18

    Sep. 20, 1991

     Nov. 3, 1998

    Sep 13 (34°) / Sep 13 (35°)
    Oct 4 (32°) / Oct. 11 (32°)
    ? / ?

     Hebron

    Oct. 1
    Oct. 11
    Oct. 20

     Sep. 19, 1991

     Oct. 28, 2010

    Sep 13 (33°)
    Oct 11 (31°)
    ?

     Smith Center KS

    Oct. 5
    Oct. 14
    Oct. 20

     Sep. 22, 1995

     Nov. 4, 1998

    Sep 13 (33°)
    ?
    ?

     Alton KS

    Sep. 27
    Oct. 3
    Oct. 14

     Sep. 13, 2014

     Oct. 23, 2007

    Sep 13 (29°)
    Sep 13 (29°)
    ?

     Plainville KS

    Oct. 8
    Oct. 15
    Oct. 25

    Sep. 20, 1995

     Nov. 3, 1998

    Sep 13 (34°)
    ?
    ?

     Beloit KS

    Oct. 7
    Oct. 15
    Oct. 25

     Sep. 13, 2014

     Nov. 10, 1998

    Sep 13 (32°)
    Sep 13 (32°)
    ?

     


    Median Dates of First Fall Freeze and Hard Freeze (1981-2010)
    (Midwestern Regional Climate Center)

    (click images to enlarge)

    Median Date of First 32-Degree Freeze Median Date of First 28-Degree Hard Freeze

     


     

    South Central Nebraska and North Central Kansas 
    30-Year Average First Frost/Freeze Dates (1983-2012)

    (click images to enlarge)

    Average 36-Degree Date (First Possible Frost)
    Average 32-Degree Date (First Freeze)
    Average 28-Degree Date (First Hard Freeze)

     


    Nebraska First Fall Frost/Freeze Averages (maps courtesy NWS Omaha/Valley)
    (click images to enlarge)

    Average date of first 36-degree temps

    Average date of first 32-degree temps

    Average date of first 28-degree temps

     



     Average First Fall 32-Degree Dates for Kansas (courtesy the Kansas State Climatologist)

    (click to enlarge)



    A Look Back At The Unusually Early Frost/Freeze of September 1974:

    One of the earliest freezes on record in parts of South Central Nebraska occurred the first week of September in 1974, as many locations dropped below the freezing mark on September 3rd. A surface weather map (see below, far left thumbnail image) from September 3, 1974 depicted just why such cold temperatures were observed. An unseasonably cold airmass roared into the region behind a strong cold front. Eventually, surface high pressure set up over the region, creating an ideal situation for a record early freeze. In fact, note the hand written comment "Record early damaging frosts, corn belt area" at the top of the weather map. Cooperative Observation forms for Gothenburg and Greeley, Nebraska are also shown below. The Gothenburg observer noted "Clear. Froze. Ice. Crop Damage" on the right side of the form on the 3rd. Finally, it is interesting to note both Gothenburg and Greeley recorded freezing temperatures again just ten days later on September 13, 1974.  

    September 3, 1974 Weather Map

    (click to enlarge)

    Gothenburg, NE Observation Form
    September 1974

    (click to enlarge)

    Greeley, NE Observation Form
    September 1974

    (click to enlarge)

     

    This page was composed by the staff at the National Weather Service in Hastings, Nebraska.

    Last updated: 10/15/14


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